JACKSONVILLE, Fla. — Mitt Romney, whose 1950s manner and celebratory drink of choice call to mind a milkshake man more than a rap singer, gave a shout out Monday that left no doubt that he had spent little time listening to hip-hop.

Mr. Romney, the Republican candidate from Massachusetts by way of Michigan and Utah who enjoys a milkshake at the end of a long day, stopped by a staging area for a Martin Luther King Birthday parade here. In his dress shirt and tie, and with his unwavering smile, he walked over and posed for photographs with a group of black youngsters. Putting his arm around a teenage girl, he waved to the cameras and offered, “Who let the dogs out?” He added a tepid “woof woof.”

Somewhere, the Baha Men, the Bahamian group whose 2000 song the candidate was referencing, must have been shuddering.

Kevin Madden, one of Mr. Romney’s campaign boyz on the bus, said the candidate had been joking around and had responded to someone who asked, “Who let you out?”